1. Field of Invention
The present disclosure of invention relates to local dimming of display light sources. More particularly, example embodiments described herein relate to a method of driving backlighting light sources for a Liquid Crystal Display (LCD) panel for thereby improving display quality.
2. Description of the Related Technology
Generally, a backlit flat panel display such as a liquid crystal display (LCD) apparatus includes an LCD panel displaying an image using optical transmittance of liquid crystal molecules and a backlight assembly disposed below the LCD panel to provide the LCD panel with back lighting.
The typical LCD panel includes an array substrate, a color filter substrate and a liquid crystal layer. The array substrate includes a plurality of pixel electrodes and a plurality of thin-film transistors (TFTs) electrically connected to the pixel electrodes. The color filter substrate is spaced apart to face the array substrate and has a common electrode and a plurality of color filters. The liquid crystal layer is interposed between the array substrate and the color filter substrate. When an electric field is generated between the pixel electrode and the common electrode and thus applied to the liquid crystal layer, the arrangement of the liquid crystal molecules of the liquid crystal layer is altered to change the optical transmissivity of the liquid crystal layer. Light such as that provided from a backlighting source and passed through the liquid crystal layer is altered thereby so that a desired image is displayed. The LCD panel can display a white image of a relatively high luminance when the optical transmittance is increased to its maximum, and the LCD panel displays a relatively black image of a relatively low luminance when the optical transmittance is decreased to its minimum.
Recently, a method of local dimming of individual blocks of a backlight assembly having a plurality of driving blocks has been proposed. In the method of local dimming, the driving blocks of the backlight assembly are individually controlled according to the gray scale of an image displayed on the LCD panel. When the backlight assembly includes a multi-lamp module, the backlight assembly uses a method of one-dimensional local dimming that may vary according to lamp shape.
In the method of one-dimensional local dimming, the backlight assembly is divided into a plurality of light source blocks, and the light source blocks are individually driven according to the gray scale of an image displayed on the LCD panel corresponding to the area of the light source blocks.
In the method of one-dimensional local dimming, an image area far away from the lamp may suffer from luminance clipping due to insufficient luminance. As a result, image areas having different gray scale values may look substantially the same and image contrast thus suffers. In addition, switching of individual backlight blocks in between continuous frame images may cause a flickering effect to be seen in boundary areas of adjacent light source blocks.